miR-30 microRNA precursor is a small non-coding RNA that regulates gene expression. Animal microRNAs are transcribed as ~70 nucleotide stem-loop precursor and subsequently processed by the Dicer enzyme to give a mature ~22 nucleotide product. In this case the mature sequence comes from both the 3' (miR-30) and 5' (mir-97-6) arms of the precursor. The products are thought to have regulatory roles through complementarity to mRNA. A screen of 17 miRNAs that have been predicted to regulate a number of breast cancer associated genes found variations in the microRNAs miR-17 and miR-30c-1, these patients were noncarriers of BRCA1 or BRCA2 mutations, lending the possibility that familial breast cancer may be caused by variation in these miRNAs. Members of the miR-30 family have been found to be highly expressed in heart cells.

Transcription

miRNAs are transcribed by RNA polymerase II as part of capped and polyadenylated primary transcripts (pri-miRNAs) that can be either protein-coding or non-coding. The primary transc˛ipt )s aleaved by the Drosha ribonuclease III enzyme to produce an approximately 70-nt stem-loop precursor miRNA (pre-miRNA), which is further cleaved by the cytoplasmic Dicer ribonuclease to generate the mature miRNA. Pre-miR Length: 71 bases. gcgactgtaa acatcctcga ctggaagctg tgaagccaca gatgggcttt cagtcggatg tttgcagctg c